The correct answer is (a) Bodha Gaya.
Kumaradevi, a queen of Govinda Chandra Gahadavala, constructed Dharma-Chakra-JinaVihara at Bodha Gaya. Bodha Gaya is a town and a notified area committee in Gaya district in the Indian state of Bihar. It is famous as the place where Gautama Buddha attained enlightenment under the Bodhi tree. The Mahabodhi Temple, a UNESCO World Heritage Site, is located here.
Rajgrih, Kushinagar, and Sarnath are also important Buddhist sites, but there is no evidence that Kumaradevi constructed any temples or monasteries at these places.
Rajgrih is a town in the Indian state of Bihar. It was the capital of the Magadha kingdom during the time of the Buddha. The Mahabodhi Temple is located here.
Kushinagar is a town in the Indian state of Uttar Pradesh. It is the place where the Buddha attained Mahaparinirvana. The Mahaparinirvana Temple is located here.
Sarnath is a town in the Indian state of Uttar Pradesh. It is the place where the Buddha gave his first sermon after attaining enlightenment. The Dhamek Stupa is located here.